When does the rodeo in Houston TX end? How much does it cost?

I read on the Houston Rodeo website that the Houston Rodeo tickets were seven dollars and that included admission into the Reliant Park for the Livestock show, Carnival, Rides, and exhibits. You can get those tickets at the gate the day you go or I think you can purchase them at the box office the days before. You can purchase all your concert tickets online or at any ticketmaster outlet. I wanted to know if the rodeo has any wheelchairs i can rent. I plan on going with my grandmother who is visiting from Cali, my mom and several family friends? However, my grandma has a bad leg and cannot walk long distances and she has a cane? Is there a motorized scooter she can rent over there?